Unstable Retraction Heights UCCNC - Fusion 360!!!

[ElierTL]

Hello guys,

I'm reaching out for some assistance. I've encountered an issue that I can't seem to grasp. My only suspicion is that there might be a misconfiguration in UCNCNC or in the Fusion 360 postprocessor.

The problem arises when exporting the .nc file from Fusion 360 to uccnc. As the process begins, erratic and imprecise movements are generated in the retraction heights. These heights increase significantly in some instances and, in other cases, even go into negative values over the material. Additionally, in some cases, it simply moves directly without raising the tool to the starting point. Honestly, I can't understand what's happening, as it's quite unstable and unpredictable. It's possible that there might also be a misconfiguration in Fusion, but I've double-checked the heights multiple times, and they should be functioning correctly. Another issue I've noticed is that when I close the file and reload it, the origin becomes misconfigured. This behavior is quite puzzling, and I can't explain it in detail. I would sincerely appreciate any guidance on this.

In Fusion, I'm using the default postprocessor for UCCNC.

It's worth noting that when I use Rhinocam software, I haven't encountered any issues while testing in "demo" mode and when connected to the CNC machine. Another thing to mention is that due to the retraction instabilities in Fusion, I've been running tests without connecting the machine, mainly to avoid potential collisions.

I've provided some images and a video for reference.








https://www.youtube.com/watch?v=lhk_Gnd ... -labsWorks


Any help would be greatly appreciated.

[ger21]

Do you have tool lengths entered in your tool table? If so, it could be the G43 tool length offset commands.
Otherwise, my guess is that your Z axis is possibly losing steps and losing position.
Those are the only two things I can think of that would result in "random" Z axis position errors.

[ElierTL]

Hello! Thank you for your response. I am attaching 2 files with a very simple example machined in Fusion 360 and Rhinocam.

In Rhinocam, I use a postprocessor for Mach 3mill, and it works flawlessly, just the way I'm looking for. It raises the Z-axis before starting the path to the starting point. On the other hand, in Fusion 360, I have tried using the postprocessors for Mach3 mill and UCCNC. However, it doesn't correctly perform the initial Z-axis lift; it moves directly to the starting point (dragging the tool through the material) and generates random heights every time I close and reload the file.

From what I've found, it seems to be omitting "G53 G0 GZ" or something might be happening with the G53 option, as when I choose the "Clearance Height" option, it doesn't generate random lifts. However, I have to manually move to a safe Z-axis height, which leaves me somewhat puzzled since Rhinocam performs the initial lift perfectly despite being a much older version.

I would appreciate any clarification. Thank you very much for your help!